CN104614072A - Total-reflection mirror based two-dimensional spectral measurement device and method - Google Patents

Abstract

A two-dimensional spectrum measurement device based on a total reflection mirror, comprising: a beam splitter, a square cylindrical four-sided mirror, a first time-delay mirror, a second time-delay mirror, a third time-delay mirror, a fourth Time-delay reflector, spatial filter, attenuation sheet, first concave reflector, sample, second concave reflector, light baffle and spectrum measurement device, the present invention has no transmission element, so there is no dispersion effect and narrow spectrum brought by transmission At the same time, it eliminates the beam shift problem caused by beam delay adjustment, making the device more compact and stable, and can perform spectral detection in a wide spectral range. The pump-probe spectrum of the sample can also be detected simultaneously on the same device for phase correction of two-dimensional spectra.

Description

Two-dimensional spectrum measurement device and measurement method based on total reflection mirror

technical field

The invention relates to spectrum measurement, in particular to a two-dimensional spectrum measurement device and measurement method based on total reflection.

Background technique

Two-dimensional spectroscopy has only been developed in recent decades, especially two-dimensional electronic spectroscopy, which has only been developed in recent ten years. Compared with the one-dimensional spectrum, the two-dimensional spectrum whose two dimensions are frequencies can reveal some information hidden under the one-dimensional spectrum. Two-dimensional spectroscopy is widely used to detect electronic and vibrational energy levels of substances, analyze molecular structures; detect photosynthetic processes of photosynthetic substances; quantum well structures of semiconductors, etc.

At present, most devices used for two-dimensional spectrum measurement use beam splitters to generate four laser beams. Due to the limitations of the beam splitter itself on the applicable wavelength, the device cannot operate in a large spectral range. measure within. Moreover, the beam splitter may introduce dispersion, which will affect the final measurement result. Although it was proposed to use a total reflection mirror for measurement [see literature 1: Zhang Y, Meyer K, Ott C, et al. Passively phase-stable monolithic all-reflectivetwo-dimensional electronic spec-troscopy based on a 4-quadrantmirror[C] //Journal of Physics:Conference Series.IOP Publishing,2014,488(14):142001.], but in order to ensure that the position of the reflected beam has a small offset when the translation stage moves, the device must let 4 The inclination angle of the block reflector is small, which requires a longer optical path to distinguish the delayed front and rear beams, resulting in excessive divergence of the beams and mixing of the four beams, which affects subsequent measurements.

Contents of the invention

In order to overcome the problems of the above-mentioned technologies, the present invention aims to provide an experimental device capable of measuring two-dimensional spectra in a wide spectral range.

Technical solution of the present invention is as follows:

A two-dimensional spectrum measurement device based on a total reflection mirror, characterized in that its composition includes: a beam splitter, a square cylinder four-sided mirror, a first time-delay mirror, a second time-delay mirror, and a third time-delay reflection mirror, the fourth time-delay reflector, spatial filter, attenuation sheet, first concave reflector, sample, second concave reflector, light baffle and spectral measuring device, and the described square cylinder four-sided reflector is a square cylinder The four outer surfaces are reflectors of reflectors, and the first delay reflector, the second delay reflector, the third delay reflector, and the fourth delay reflector are all composed of two reflector surfaces, The angles between the two mirrors are equal, along the direction of the incident laser light are the beam splitter baffle and the square cylinder four-sided reflector in turn, the center of the incident laser beam and the four beam splitter baffles The center of the rectangle formed by the small hole coincides, the axis of the four-sided mirror of the square cylinder is vertical and a relative edge is coplanar with the axis of symmetry passing through the center of the beam splitter baffle, in the square The first time-delay reflector, the second time-delay reflector, the third time-delay reflector and the fourth time-delay reflector are respectively set up and down on both sides of the cylinder four-sided reflector, and the first time-delay reflector The reflector, the second time-delay reflector, the third time-delay reflector and the fourth time-delay reflector are installed on respective controllable translation stages, so that the incident laser light passes through the beam splitter baffle The four parallel beams emitted from the four small holes: the reference beam, a beam, b beam and c beam, are respectively incident and reflected by the two adjacent surfaces of the four-sided mirror of the square cylinder, and then respectively passed through the first extension Time-delay reflector, the second time-delay reflector, the 3rd time-delay reflector and the 4th time-delay reflector reflect and shoot to the other two adjacent surfaces of described square cylinder four-sided reflector, still be four bundles parallel after reflection Beams, in the directions of the four parallel beams are the spatial filter, the first concave reflector, the sample, the second concave reflector, the light baffle and the spectral measurement device, the first concave reflector and the second The concave mirrors are opposite and confocal planes, the sample is located at the confocal plane of the first concave mirror and the second concave mirror, the attenuation sheet is on the reference optical path before the sample, and the The four laser beams are incident on the first concave reflector and focused on the sample, and the four laser beams passing through the sample are transformed into four parallel beams again through the second concave reflector. After the four parallel beams pass through the light baffle, Only let the reference light and signal light pass through, and finally enter the spectrometer.

The first time-delay reflector, the second time-delay reflector, the third time-delay reflector, and the fourth time-delay reflector are all composed of two mirror surfaces, and the angle between the two mirror surfaces is a right angle.

A method for performing two-dimensional spectrum measurement using the above-mentioned two-dimensional spectrum measurement device, the method includes the following steps:

1) Calibrate the optical path: replace the sample with a CCD, move the position of the CCD so that the CCD is located at the focal plane of the first concave mirror, at this time the four laser beams should overlap on the CCD, otherwise, by adjusting the The first time-delay reflector, the second time-delay reflector, the third time-delay reflector, and the fourth time-delay reflector that do not overlap the light beams pass through until the four laser beams overlap; The light beams of the first delay reflector, the second delay reflector, the third delay reflector, and the fourth delay reflector are reference beam, a beam, b beam, and c beam respectively, and then block them on the beam splitting baffle The two small holes allow only the reference beam and a beam to pass through, and adjust the translation stage of the delay mirror corresponding to the second delay mirror until interference fringes are generated on the CCD. Spatial overlap; then block the a beam, keep the reference beam, let go of the b beam of the two beams just blocked, and adjust the translation stage of the third time-delay mirror corresponding to the b beam until the same interference occurs on the CCD fringes; adjust the translation stage of the fourth time-delay reflector of the last c-beam light in the same way until interference fringes also appear on the CCD. CCD, place the sample at the focal plane of the first concave mirror, at this time, due to the excitation of the a beam, the b beam, and the c beam, the sample will generate signal light, and the direction of the signal light is consistent with the direction of the reference light; in front of the sample inserting the attenuation sheet into the reference light path, so that the intensity of the reference light is equivalent to the signal light;

2) After passing through the sample, the four beams of laser light are incident on the second concave mirror and become four beams of parallel beams again, and then only the reference light and signal light are allowed to pass through the light baffle with a small hole. Light is coincident in space;

3) Use a spectrometer to detect the spectral interference fringes of the reference light and the signal light: adjust the translation stage of the first delay mirror corresponding to the reference light to ensure that the reference light is first incident on the sample, and at the same time ensure that the density of the interference fringes is appropriate. When adjusting the optical path, you can block the reference light first, and use a spectrometer to check whether there is signal light. If not, fine-tune the position of the sample to ensure that the sample is indeed located on the focal plane. The signal light should be a beam, b beam, and c beam. The generated nonlinear signal should not generate signal light after blocking any beam of light;

4) After observing the interference fringes, use a spectrometer to collect data on the sample, the method is as follows:

The first step: move the translation stage of the second time-delay mirror, the translation stage of the third time-delay mirror and the translation stage of the fourth time-delay mirror, so that the a beam and the b beam are all ahead of the c beam, and the leading time The interval is recorded as T, and T can take a value from 0 to hundreds of femtoseconds. At this time, the delay between beam a and beam b is 0;

Step 2: Move the translation platform of the second time-delay reflector so that beam a is ahead of beam b by time τ; then move the translation platform of the second delay mirror so that beam a approaches beam b with a fixed step size Δt until Coincidentally, every time the translation platform of the second time-delay mirror is moved, the spectrometer collects interference fringes once; in this process, except for the a beam, other beams should not change;

Step 3: Move the translation stage of the third time-delay mirror, make b beam ahead of a beam time τ, and ensure that the delay between a beam and beam c is still T; then move the translation of the third time-delay mirror stage, so that the b beam approaches the a beam with a fixed step size Δt until it coincides; every time the translation stage of the third time-delay mirror is moved, the spectrometer collects interference fringes once; in this process, except for the b beam, other beams are should not change;

Step 4: Block the b beam and the reference beam. At this time, the a beam is still ahead of the c beam by time T; let the c beam be the probe light, and the a beam be the pump light, and the spectrometer performs pump detection to obtain the pump light of the sample. Probing absorption spectra for phase correction of 2D spectra.

Technical effect of the present invention is as follows:

The four laser beams will have different delays after passing through the mirror installed on the translation stage, so that although the four beams of light focused on the sample are coincident in space, they are all dispersed in time [see Figure 2 of the manual] The reference light, beam a, beam b, beam c] in the. The reference light is first incident on the sample, followed by beam a, beam b, and beam c in sequence. The time delay between beam a and beam b is τ, and the time delay between beam b and beam c is T. The delay can be precisely controlled to the order of hundreds of attoseconds with the translation stage. After the sample is irradiated by the beams a, b, and c, due to the nonlinear effect, a signal light will be generated in the direction of phase matching. Since the beams a, b, and c are on the three vertices of the same rectangle, the phase matching angle It is exactly at the fourth vertex of the rectangle, that is, it is consistent with the optical path of the reference light, so the signal light will also be incident on the spectrometer and form spectral interference fringes with the reference light for heterodyne detection.

In the present invention, the square cylinder reflector with four sides being reflectors divides the four laser beams into two parts, and the two parts face different directions respectively, and then re-enter the square cylinder after passing through the reflector on the translation platform. mirror. When the moving direction of the translation stage is parallel to the direction of the laser incident on the reflection mirror of the translation stage, even when the translation stage is displaced, the position of the reflected beam will not move. This ensures that the outgoing four beams are still on the same rectangle, and ensures that the direction of the signal light will not change due to the movement of the translation stage, so that the signal light can always coincide with the optical path of the reference light. Using such a design does not need a long optical path to distinguish the beams before and after the delay, which greatly reduces the divergence of the beam spot caused by the long optical path, which is beneficial to the measurement of the subsequent optical path, and the whole device can also be made compact.

In the present invention, the centers of the four small holes of the spatial filter are also located above the four corners of the rectangle, and the size of the rectangle should be consistent with the size of the rectangle formed by the four holes in the beam splitter baffle. The hole in the spatial filter can be slightly larger than the hole in the beamstop. The focal planes of the first concave mirror and the second concave mirror) coincide.

The present invention needs to constantly move the translation platform to adjust the time delay τ between the beam a and the beam b during data collection, so it needs programming to control the translation platform and the spectrometer to automatically complete the data collection.

The present invention does not use transmission elements such as beam splitters, which reduces the dispersion that may be introduced by the transmission elements. Because all reflective mirror elements are used, the present invention can perform measurements in a wide spectral range from ultraviolet to near infrared. At the same time, the movement of the time-delayed translation platform in the present invention will not cause the deviation of the direction of the signal light, which contributes to the stability of the interference spectrum.

Description of drawings

Fig. 1 is the schematic diagram of the optical path of the two-dimensional spectrum measuring device based on the total reflection mirror of the present invention

Figure 2 is a schematic diagram of the timing of the four beams incident on the sample

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the present invention should not be limited thereby.

First please refer to Fig. 1, Fig. 1 is the optical path schematic diagram of the two-dimensional spectrum measurement device based on the total reflection mirror of the present invention, as can be seen from the figure, the two-dimensional spectrum measurement device based on the total reflection mirror of the present invention comprises: a beam splitter baffle 1 , square cylinder four-sided reflector 2, first delay reflector 3, second delay reflector 4, third delay reflector 5, fourth delay reflector 6, spatial filter 7, attenuation sheet 8, First concave reflector 9, sample 10, second concave reflector 11, light blocking plate 12 and spectrometer 13, described square cylinder four-sided reflector 2 is a reflector whose four outer sides of square cylinder are reflectors, The first time-delay reflector 3, the second time-delay reflector 4, the third time-delay reflector 5, and the fourth time-delay reflector 6 are all made of two mirror surfaces, and the angles between the two mirror surfaces are equal , along the direction of the incident laser light are the beam splitter baffle 1 and the square cylindrical four-sided mirror 2 in turn, the center of the incident laser beam and the four small holes on the beam splitter baffle 1 form a rectangle The center coincides, the axis of the four-sided mirror 2 of the square cylinder is vertical and a relative edge is coplanar with the axis of symmetry passing through the center of the beam splitter baffle 1, on the four sides of the square cylinder The first delay reflector 3, the second delay reflector 4, the third delay reflector 5 and the fourth delay reflector 6 are respectively set up and down on both sides of the reflector 2, and the first delay reflector 6 is arranged respectively. The time-delay reflector 3, the second time-delay reflector 4, the third time-delay reflector 5 and the fourth time-delay reflector 6 are respectively installed on respective controllable translation stages, so that the incident laser light passes through the The four beams of parallel light beams emitted from the four small holes of the beam splitter baffle 1: the reference beam, the a beam, the b beam and the c beam are respectively incident and reflected by the two adjacent surfaces of the four-sided mirror 2 of the square cylinder, and then Respectively through the first time-delay reflector 3, the second time-delay reflector 4, the third time-delay reflector 5 and the fourth time-delay reflector 6 reflection to the described square cylinder four-sided reflector 2 The other two adjacent surfaces are still four parallel light beams after reflection, and in the direction of the four parallel light beams are the spatial filter 7, the first concave reflector 9, the sample 10, the second concave reflector 11, the blocking Optical plate 12 and spectrometer 13, the first concave reflector 9 and the second concave reflector 11 are opposite and in a confocal plane, and the sample 10 is located at the confocal plane of the first concave reflector 9 and the second concave reflector 11 At the plane, the attenuation sheet 8 is on the reference optical path before the sample 10, the four laser beams are incident on the first concave reflector 9 and focused on the sample 10, and the four laser beams passing through the sample 10 are again After passing through the second concave reflector 11 , it becomes four parallel beams again. After the four parallel beams pass through the light baffle 12 , only the reference light and the signal light pass through, and finally enter the spectrometer 13 .

A method for performing two-dimensional spectrum measurement using the above-mentioned two-dimensional spectrum measurement device, the method includes the following steps:

1) Calibrate the optical path: replace the sample 10 with a CCD, and move the position of the CCD so that the CCD is located at the focal plane of the first concave reflector 9. At this time, the four laser beams should overlap on the CCD; otherwise, by adjusting the The first time-delay reflector 3, the second time-delay reflector 4, the third time-delay reflector 5, and the fourth time-delay reflector 6 passed by the non-overlapping light beams, until the four laser beams overlap; Determine the light beams passing through the first time-delay reflector 3, the second time-delay reflector 4, the third time-delay reflector 5, and the fourth time-delay reflector 6 as reference beam, a light beam, b light beam, c light beam, respectively light beam, then block two small holes on the beam splitter baffle plate 1, only allow the two beams of the reference beam and the a beam to pass through, adjust the translation stage of the delay reflector corresponding to the second delay reflector 4, until the CCD Interference fringes are generated, which means that the two beams have overlapped in time and space; then block the a beam, keep the reference beam, let go of the b beam of the two beams just blocked, and adjust the third delay corresponding to the b beam The translation stage of the reflector until interference fringes also appear on the CCD; adjust the translation stage of the fourth time-delay mirror of the last c-beam light in the same way until interference fringes also appear on the CCD. The position should be coincident in time and space; then the CCD is removed, and the sample 10 is placed on the focal plane of the first concave mirror 9. At this time, due to the excitation of the a beam, the b beam, and the c beam, the sample 10 will generate signal light , the direction of the signal light is consistent with the direction of the reference light; the attenuation sheet 8 is inserted in the reference light path in front of the sample 10, so that the intensity of the reference light is equivalent to the signal light;

2) After passing through the sample 10, the four beams of laser light are incident on the second concave reflector 11 and become four beams of parallel beams again, and then only the reference light and the signal light are allowed to pass through the light baffle plate 12 with a small hole. Light and signal light are coincident in space;

3) Use a spectrometer to detect the spectral interference fringes of reference light and signal light: adjust the translation stage of the first time-delay mirror 3 corresponding to the reference light to ensure that the reference light is first incident on the sample, and at the same time ensure that the density of the interference fringes is appropriate , when adjusting the optical path, you can block the reference light first, and use the spectrometer 13 to check whether there is signal light. If not, fine-tune the position of the sample 10 to ensure that the sample is indeed located on the focal plane. The signal light should be a light beam, b light beam and The non-linear signal generated by c beams together, after blocking any beam of light, no signal light should be generated;

4) After observing the interference fringes, use the spectrometer 13 to collect data on the sample (10), the method is as follows:

The first step: move the translation platform of the second time-delay mirror 4, the translation platform of the third time-delay mirror 5 and the translation platform of the fourth time-delay mirror 6, so that the a beam and the b beam are all ahead of the c beam, The leading time interval is recorded as T, and T can take a value from 0 to hundreds of femtoseconds, at this time, the delay between beam a and beam b is 0;

The second step: move the translation platform of the second time-delay mirror 4, so that the a beam is ahead of the b beam by time τ; then move the translation platform of the second time-delay mirror 4, so that the a beam approaches the b beam with a fixed step length Δt , until coincidence, every time the translation stage of the second delay mirror 4 is moved, the spectrometer 13 collects interference fringes once; in this process, except for the a beam, other beams should not change;

The third step: move the translation stage of the third time-delay mirror 5, so that the b beam is ahead of the a beam time τ, and ensure that the delay between the a beam and the beam c is still T; then move the third time-delay mirror 5 The translation platform of the b beam makes the b beam approach the a beam with a fixed step size Δt until it coincides; every time the translation platform of the third time-delay mirror 5 is moved, the spectrometer 13 collects interference fringes once; this process is except for the b beam , the other beams should not change;

Step 4: block the b beam and the reference beam, and at this time, the a beam is still ahead of the c beam by time T; let the c beam be the probe light, and the a beam be the pump light, and the spectrometer 13 performs pump detection to obtain the sample 10 Pump-probe absorption spectroscopy for phase correction of 2D spectra.

The first time-delay mirror 3 , the second time-delay mirror 4 , the third time-delay mirror 5 , and the fourth time-delay mirror 6 described in the embodiment are all right-angle mirrors.

Assume in the present embodiment that what is incident on the first time-delay reflector (3) is the reference light; what is incident on the second time-delay reflector (4) is light beam a; ) is the beam c; the incident on the fourth delay mirror (6) is the beam b. Respectively adjust the first delay reflector 3, the second delay reflector 4, the third delay reflector 5, the fourth delay reflector 6, so that the four outgoing beams can pass through the spatial filter 7 respectively, and the four The position where the laser beam passes through the hole should correspond to the position on the beam splitter baffle 1 . This ensures that the emitted four beams are still parallel to each other and still located on the four vertices of the rectangle.

In this example, the attenuation sheet for attenuating the reference light is placed after the spatial filter 7 . The order of magnitude of the attenuated reference light intensity should be comparable to that of the signal light.

At this time, due to the excitation of light beams a, b, and c, the sample will generate signal light, and the direction of the signal light is consistent with the direction of the reference light.

The data obtained above can be used to calculate the two-dimensional spectrum of the sample.

Claims (3)

1. A two-dimensional spectral measurement device based on total reflection mirror, characterized in that its composition comprises: beam splitter baffle (1), square cylinder four-sided reflector (2), the first time-delay reflector (3), the first Second delay reflector (4), third delay reflector (5), fourth delay reflector (6), spatial filter (7), attenuation sheet (8), first concave reflector (9) , sample (10), second concave reflector (11), baffle plate (12) and spectrum measuring device (13), described square cylinder four-sided reflector (2) is that the four outer sides of square cylinder are The reflector of reflector, described first delay reflector (3), the second delay reflector (4), the 3rd delay reflector (5), the 4th delay reflector (6) all by Consisting of two reflecting mirrors, the angles between the two mirrors are equal, along the direction of the incident laser light are the beam splitter baffle (1) and the square cylinder four-sided reflector (2), and the incident laser beam The center coincides with the center of the rectangle formed by four small holes on the beam splitter baffle (1), the axis of the square cylinder four-sided reflector (2) is vertical and a relative edge crosses the The central symmetry axes of the beam splitter baffle (1) are coplanar, and the first time-delay reflector (3), the second delay reflector (3) and the second delay reflector (3) are respectively set up and down on both sides of the square cylinder four-sided reflector (2). Two delay reflectors (4), the 3rd delay reflector (5) and the 4th delay reflector (6), described first delay reflector (3), the second delay reflector (4) ), the third time-delay reflector (5) and the fourth time-delay reflector (6) are respectively installed on the respective controllable translation stages, so that the incident laser light passes through the beam splitter baffle (1) The four beams of parallel light beams emitted from the four pinholes: the reference beam, the a beam, the b beam and the c beam are respectively incident and reflected by the two adjacent surfaces of the four-sided mirror (2) of the square cylinder, and then respectively passed through the The first time-delay reflector (3), the second time-delay reflector (4), the third time-delay reflector (5) and the fourth time-delay reflector (6) are reflected and directed to the square cylinder The other two adjacent surfaces of the four-sided reflector (2) are still four beams of parallel beams after reflection, and in the direction of the four beams of parallel beams, the spatial filter (7), the first concave reflector (9), and the sample are followed successively. (10), the second concave reflector (11), light blocking plate (12) and spectral measurement device (13), the first described concave reflector (9) and the second concave reflector (11) are relative and confocal plane, the sample (10) is located at the confocal plane of the first concave mirror (9) and the second concave mirror (11), and the attenuation sheet (8) is in front of the sample (10) On the reference optical path, the four beams of laser light are incident on the first concave reflector (9) and focused onto the sample (10), and the four beams of laser light passing through the sample (10) pass through the second concave reflector (11) again Change into four beams of parallel light beams, after the four beams of parallel beams pass through the light baffle (12), only the reference light and signal light are allowed to pass through, and finally enter the spectrometer (13). 2. The two-dimensional spectrum measurement device according to claim 1, characterized in that said first time-delay reflector (3), the second time-delay reflector (4), and the third time-delay reflector (5) The fourth time-delay reflecting mirror (6) is composed of two reflecting mirror surfaces, and the angle between the two mirror surfaces is a right angle. 3. Utilize the two-dimensional spectrum measuring device described in claim 1 to carry out the method for two-dimensional spectrum measurement, it is characterized in that the method comprises the following steps: 1) Calibrate the optical path: replace the sample (10) with a CCD, and move the position of the CCD so that the CCD is located at the focal plane of the first concave mirror (9). At this time, the four laser beams should overlap on the CCD, otherwise , by adjusting the first time-delay mirror (3), the second time-delay mirror (4), the third time-delay mirror (5), the fourth time-delay mirror mirror (6), until the four beams of laser overlap; Determine that the light beams passing through the first time-delay reflector (3), the second time-delay reflector (4), the third time-delay reflector (5), and the fourth time-delay reflector (6) are reference beams respectively , light beam a, light beam b, and light beam c, and then block two small holes on the beam splitting baffle (1), allowing only the reference beam and a light beam to pass through, and adjust the corresponding position of the second time-delay reflector (4) The translation stage of the time-delay mirror until interference fringes are generated on the CCD. At this time, it means that the two beams have overlapped in time and space; then block the a beam, keep the reference beam, and let go of the b beam of the two beams just blocked , adjust the translation stage of the third time-delay reflector corresponding to the b beam until interference fringes also appear on the CCD; adjust the translation stage of the fourth time-delay reflector of the last c-beam light in the same way until the same Interference fringes appear, and the four beams of light should coincide in time and space at the position of the CCD after completion; then the CCD is removed, and the sample (10) is placed on the focal plane of the first concave reflector (9). When the light beam, b beam, and c beam are excited, the sample (10) will generate signal light, and the direction of the signal light is consistent with the direction of the reference light; insert the attenuation sheet (8) into the reference light path in front of the sample (10), making the intensity of the reference light equal to the signal light; 2) After passing through the sample (10), the four beams of laser light are incident on the second concave mirror (11) and become four beams of parallel beams again, and then only the reference light and signal The light passes through, at this time the reference light and the signal light are coincident in space; 3) Use a spectrometer to detect the spectral interference fringes of the reference light and the signal light: adjust the translation stage of the first delay mirror (3) corresponding to the reference light to ensure that the reference light is first incident on the sample, and at the same time ensure that the interference fringes If the density is appropriate, the reference light can be blocked first when adjusting the light path, and the spectrometer (13) can be used to check whether there is signal light. If not, fine-tune the position of the sample (10) to ensure that the sample is indeed located on the focal plane. The signal light should be The non-linear signal jointly generated by beam a, beam b and beam c, after blocking any beam of light, no signal light should be generated; 4) After observing the interference fringes, use the spectrometer (13) to collect data on the sample (10), the method is as follows: The first step: move the translation platform of the second time-delay mirror (4), the translation platform of the third time-delay mirror (5) and the translation platform of the fourth time-delay mirror (6), so that a light beam and b light beam Both are ahead of beam c, the leading time interval is recorded as T, T can take a value of 0-hundreds of femtoseconds, at this time, the delay between beam a and beam b is 0; The second step: move the translation platform of the second time-delay mirror (4), so that the a beam is ahead of the b beam by time τ; then move the translation platform of the second time-delay mirror (4), so that the a beam is at a fixed step size Δt Approaching the b beam until coincidence, every time the translation stage of the second time-delay reflector (4) is moved, the spectrometer (13) collects interference fringes once; in this process, except for the a beam, other beams should not change ; The third step: move the translation platform of the third time-delay reflector (5), make b beam lead a beam time τ, and ensure that the time delay between a beam and beam c is still T; then move the third time-delay reflection The translation stage of the mirror (5) makes the b beam approach the a beam with a fixed step length Δt until they coincide; every time the translation stage of the third time-delay mirror (5) is moved, the spectrometer (13) collects an interference fringes; during this process, except for the b beam, the other beams should not change; Step 4: block the b beam and the reference beam, and at this time, the a beam is still ahead of the c beam by time T; let the c beam be the probe light, and the a beam be the pump light, and the spectrometer (13) performs pump detection to obtain the sample The pump-probe absorption spectrum of (10) for phase correction of 2D spectra.